Помогите решить.) 10√3*cosπ/3*cos11π/6

Question

Помогите решить.) 10√3*cosπ/3*cos11π/6

Answer 1

10 √3*cosπ/3*cosπ/6=10 √3*1/2* √3/2=7,5
cos11π/6=cos(2π-π6)=cosπ/6= √3/2
Answer:7,5
Not аt all!)